ironmark

Fast Markdown-to-HTML parser written in Rust. Fully compliant with CommonMark 0.31.2 (652/652 spec tests pass). Available as a Rust crate and as an npm package via WebAssembly.

Features

• Zero third-party parsing dependencies
• Headings (# through ######) and setext headings
• Paragraphs, emphasis, strong emphasis, inline code
• strikethrough, ==highlight==, ++underline++
• Links, reference links, autolinks (angle-bracket and bare URL/email), images
• Ordered and unordered lists with nesting, task lists (checkboxes)
• Blockquotes, horizontal rules
• Fenced and indented code blocks
• Tables with alignment
• Raw HTML passthrough
• Backslash escapes and HTML entities

JavaScript / TypeScript

Install

npm install ironmark

Usage (Node.js)

WASM is embedded and loaded synchronously — no init() needed:

import { parse } from "ironmark";

const html = parse("# Hello\n\nThis is **fast**.");

const bytes = new TextEncoder().encode("# Hello from bytes");
const html2 = parse(bytes);

Usage (Browser / Bundler)

Call init() once before using parse():

import { init, parse } from "ironmark";

await init();

const html = parse("# Hello\n\nThis is **fast**.");

init() is idempotent (safe to call multiple times) and can optionally take a custom URL to the .wasm file.

Options

import { parse } from "ironmark";

const html = parse("line one\nline two", {
  hardBreaks: false, // every newline becomes <br /> (default: true)
  enableHighlight: true, // ==highlight== → <mark> (default: true)
  enableStrikethrough: true, // ~~strike~~ → <del> (default: true)
  enableUnderline: true, // ++underline++ → <u> (default: true)
  enableTables: true, // pipe tables (default: true)
  enableAutolink: true, // bare URLs & emails → <a> (default: true)
  enableTaskLists: true, // - [ ] / - [x] checkboxes (default: true)
});

Build from source

npm run setup:wasm
npm run build

Rust

Add to your project

cargo add ironmark

Usage

use ironmark::{parse, ParseOptions};

fn main() {
    let html = parse("# Hello\n\nThis is **fast**.", &ParseOptions::default());
    println!("{html}");
}

With options

use ironmark::{parse, ParseOptions};

fn main() {
    let options = ParseOptions {
        hard_breaks: true,
        enable_strikethrough: false, // disable ~~strikethrough~~
        enable_autolink: true,      // bare URLs & emails → <a>
        enable_task_lists: true,    // - [ ] / - [x] checkboxes
        ..Default::default()
    };

    let html = parse("line one\nline two", &options);
    println!("{html}");
}

Troubleshooting

wasm32-unknown-unknown target not found with Homebrew Rust

The build scripts prepend $HOME/.cargo/bin to PATH so that rustup-managed binaries take priority. If the error persists:

npm run setup:wasm

wasm-bindgen not found

npm run setup:wasm